Can kuacha also be correct?
'kuondoka' is to depart from a place, 'kuacha' is to leave an object behind
Thanks so as a translation of "to leave" it should be accepted.
is kuacha the same as 'to forget [something]'?
No ! ACHA ! is Stop! Kuacha - to stop and kusahau - to forget.
Seeing as there's absolutely no context, no sentence, just an infinitive verb in a vacuum, yes. Any word you see in a (good) dictionary for "leave" should be accepted.